“What we see in films and call holograms are typically volumetric displays,” said Bouzbib, the lead author of the work. “These are graphics that appear in mid-air and can be viewed from various angles without the need for wearing virtual reality glasses. They are called true-3D graphics.”
Here is a link to the PDF that details the work: https://hal.science/hal-04981007v1/file/FlexiVol___CHI25 (2).pdf
that is old. remember 2014: https://newatlas.com/ultrasound-3d-haptic-hologram/35032/
That research was more about the haptics. This new research is more about projecting a volumetric hologram that can also be interacted with directly.